BackgroundInformation | CNPase(2",3"-cyclicnucleotide3"-phosphodiesterase[or-phosphohydrolase],EC3.1.4.37)ispresentinveryhighlevelsinbrainandperipheralnerve.Thisenzymeisfoundalmostexclusivelyinoligo-dendrocytesandSchwanncells,thecellsthatformmyelininthecentralandperipheralnervoussystem,respectively. ImmunohistochemicallocalizationofCNPasehasshowntheenzymetoberestrictedtooligodendrocytesandSchwanncells.Theenzymeappearstobedistributedinsingleanddoubleloosewrapsofmyelinandnotincompactmyelinasearlierthoughtbymostinvestigators.CNPaseislocatedontheinnerandouterloopsofmyelin,paranodallyandneartheinnersurfaceoftheoligodendrocytemembrane.Inplaqueregionsofmultiplesclerosispatients,theenzymeisreduced,andwhenCNSmyelinisdecreased,CNPaseisoneoftheearlierproteinstobelostfromthemyelin.Inaddition,anenzymethatisprobablyidenticaltobrainCNPaseislocatedintheouterrodsegmentswithinthevisualsystem,andthisproteinisalsorecognizedbythemonoclonalantibody11-5B.Inmixedhumangliomas,theenzymelevelsarereduced,althoughabout5%oftheoligodendrocytesoccasionallyshownormalpositivestaining. |